Electron-Flask Bootstrap Template

Dependencies

Python 3.9	NodeJS 16.x

Installation

1. Clone the repository git clone ...
2. Install Python dependencies python -m pip install -r requirements.txt
3. Install node modules npm install

Running the App

Start app

• Windows: .\node_modules\.bin\electron .
• Mac OS/Linux: ./node_modules/.bin/electron .

Start app with globally installed electron

• electron .

Run the app through your web browser

• Start Flask server manually: python web_app/run_app.py

Bundling

Packaging is done in two steps:

1. A standalone Python executable containing the Flask backend is generated using PyInstaller
2. The Python executable and the electron application (electron.js) are bundled using electron-builder

NOTE: The Python executable is generated in the "one-file-mode"; All dependencies are wrapped in a single executable. When executed, the program is decompressed to a temporary directory and run in a second process from there. This has to be considered in the life-cycle management of the electron app. See killPythonSubprocesses of electron.js.

Package the app for the host platform

• npm run package (output binaries will be stored in /dist)

Cross-Platform packaging

• Not yet supported (due to lacking cross-compilation support of PyInstaller)

Why Flask?

• Using a Flask webserver for interprocess communication (ICP) comes in handy to bundle an existing Flask-based service into a desktop application. The endpoints don't have to be changed.
• For other applications there are more efficient alternatives to using Flask/HTTP for ICP, e.g. zerorpc.

Encountered Issues

• asar is read-only, .pyc files cannot be created
• When bundling the standalone Python executable in an .asar, a random filename is generated. This makes life-cycle management of the backend service difficult (see also section Bundling).

Feature Backlog

Bundling Resources with the Python Executable

• use --add-data to bundle resources with the python executables (use sys._MEIPASS to resolve paths)

• see python-eel/Eel#57

def resource_path(relative_path):
    """ Get absolute path to resource, works for dev and for PyInstaller """
    if hasattr(sys, '_MEIPASS'):
        return os.path.join(sys._MEIPASS, relative_path)
    return os.path.join(os.path.abspath("."), relative_path)

Cross-Compilation through Docker

• create a Docker image to allow building for Linux on Windows

ASAR Bundling

• When bundling the electron app in an .asar, the path to the python executable (which is copied to the resource folder) is not resolved properly